What is a .war file?
Web Application Archive · Archive · Sun Microsystems · 1999
A .war file is a Web Application Archive: a ZIP package that bundles a Java web application, its servlets, pages and libraries, for deployment to a server like Apache Tomcat.
What is a .war file used for?
A WAR is structured like a JAR but for web apps, with a WEB-INF folder holding classes, libraries and configuration. You deploy it to a servlet container, which unpacks and runs it.
Being a ZIP, it starts with the ZIP signature and opens in any archive tool for inspection.
How to open a .war file
The .war format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .war file.
Windows
- Apache Tomcat (deploy)
- 7-Zip (to inspect)
- IntelliJ IDEA
macOS
- Apache Tomcat (deploy)
- The Unarchiver
- IntelliJ IDEA
Linux
- Apache Tomcat (deploy)
- unzip
How to convert a .war file
You can convert a .war file to zip using a conversion tool or the export menu of an app that opens it.
.war file signature (magic bytes)
Programs recognise a .war file by the bytes at the start of the file, not by its name. These are the signatures for WAR. For a full breakdown, see the WAR file signature page.
| Hex signature | Offset | Note |
|---|---|---|
| 50 4B 03 04 | 0 | ZIP package (PK..) |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .war file?
A .war file is a Web Application Archive: a ZIP package that bundles a Java web application, its servlets, pages and libraries, for deployment to a server like Apache Tomcat.
How do I open a WAR file?
To inspect it, open it as a ZIP in 7-Zip. To run it, deploy it to a servlet container like Apache Tomcat by dropping it in the webapps folder.
What is the difference between a JAR and a WAR?
Both are ZIP packages of Java code. A JAR is a library or app; a WAR packages a full web application with a WEB-INF layout for a server.
How do I extract a WAR file?
Rename it to .zip and unzip it, or run jar -xvf app.war. Inside you will find WEB-INF and the web content.
Related formats
Sources
Details on this page were checked against authoritative references: